I did it with my then first grader but I am wondering now if I will start it earlier with my next ds. It felt like maybe I could have done it in K? But I am not sure. Interested to hear other responses!

4yo, *but* it was just a couple times per week, and we didn't start off with labsheets at all. I can't remember when we actually started the Orange book...but I do know that when ds8 was 4yo I set him up with a little "math play" table for just him while I chased the 2yo and 1yo. Those were crazy days! (I was too busy and sleep deprived to inflict too much learning.)

My dd was 4yo when we started doing some rod play beyond free play. She started Orange at 5yo....still, it's sporadic; not like we plow through the book iykwim.

Current 4yo is in the play stage. I'm ordering Orange for him so we'll have it next year, but am in no hurry to start.

We did do Lab Sheets, play, directed play, homemade Lab Sheets, many activities based on ideas from the First Grade Diary, ideas "stolen" from the RS Activities for AL Abacus book (some translated to rods and blocks), activities involving things I made up, and sheets my then 4 year old made himself.

And we made cards with red dots to represent 1-10 Japanese math style (two rows of 5 to make Ten, and Tally stick style, and regular numerals. And used RS place value cards and base-10 cards, and modeled three digit numers using base-10 "flats" (100s) Orange C Rods (10s) and C Rods (Units) as well as modeling them on an AL Abacus. Stuff like that.

We have Miquon for my 3.5 year old but he is really more into playing with the C-rods independently right now. I'm going to pick out some of the easier labs and put them in a binder, then let him choose which lab to do each day so it's a little more child-led exploration.

I just bought Miquon for my 6 y/o. He attended a Montessori school for 3 years where he's already spent lots of time working with place value and manipulatives. I think that Miquon used in addition with the RS games will nicely complement the Montessori style math that he's already accustomed to doing.